package org.zxyj.core.spring;

import org.apache.commons.lang.Validate;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.DisposableBean;
import org.springframework.context.ApplicationContext;
import org.springframework.context.ApplicationContextAware;
import org.springframework.context.annotation.Lazy;
import org.springframework.stereotype.Service;

/**
 * 以静态变量保存Spring ApplicationContext, 可在任何代码任何地方任何时候取出ApplicaitonContext.
 * 
 * @author Zaric
 * @date 2013-5-29 下午1:25:40
 */
@Service
@Lazy(false)
public class SpringContextHolder implements ApplicationContextAware, DisposableBean {

	private static Logger logger = LoggerFactory.getLogger(SpringContextHolder.class);

	private static ApplicationContext applicationContext = null;

	/**
	 * 取得ApplicationContext
	 */
	public static ApplicationContext getApplicationContext() {
		SpringContextHolder.assertContextInjected();
		return applicationContext;
	}

	/**
	 * 从静态变量applicationContext中取得Bean
	 */
	@SuppressWarnings("unchecked")
	public static <T> T getBean(String name) {
		SpringContextHolder.assertContextInjected();
		return (T) applicationContext.getBean(name);
	}

	/**
	 * 从静态变量applicationContext中取得Bean
	 */
	public static <T> T getBean(Class<T> requiredType) {
		SpringContextHolder.assertContextInjected();
		return applicationContext.getBean(requiredType);
	}

	/**
	 * 清除SpringContextHolder中的ApplicationContext
	 */
	public static void clear() {
		if (logger.isDebugEnabled()) {
			logger.debug("Clearing ApplicationContext from SpringContextHolder");
		}
		applicationContext = null;
	}

	/**
	 * 检查ApplicationContext不为空
	 */
	private static void assertContextInjected() {
		Validate.notNull(applicationContext,
				"applicaitonContext属性未注入, 请在applicationContext.xml中定义SpringContextHolder.");
	}

	/**
	 * 实现ApplicationContextAware接口, 注入Context到静态变量中
	 */
	public void setApplicationContext(ApplicationContext applicationContext) {
		logger.debug("Injecting applicationContext[{}] to SpringContextHolder", applicationContext);

		SpringContextHolder.applicationContext = applicationContext;
	}

	/**
	 * 实现DisposableBean接口, 在Context关闭时清理静态变量.
	 */
	public void destroy() throws Exception {
		SpringContextHolder.clear();
	}

}